Despite the efficacy of antipsychotic medication a substantial subgroup of recently hospitalized schizophrenic patients do not respond satisfactorily to an initial course of antipsychotic medication. It is clear in the field at the moment that the two most commonly employed alternative strategies for treating such patients are to increase the dosage substantially or switch to another antipsychotic drug. We are not aware of any systematic controlled clinical trials which provide guidance for the clinician in this context. This issue is made even more critical by increasing pressure to shorten length of hospital stay, with many clinicians feeling pressured to alter the pharmacologic treatment plan after one or two weeks if substantial improvement has not occurred. This may result in patients receiving unnecessarily high doses of being prematurely switched to a different antipsychotic drug. Research in this area is of considerable clinical and public health importance. This study will compare the relative efficacy and adverse effects of three alternative stategies for patients who fail to meet a priori criteria for improvement following a four week course of fluphenazine HCL 20 mg/day. "Nonresponders" will be randomly assigned double-blind to 1) continue on fluphenazine 20 mg/day for an additional four weeks; 2) receive fluphenazine 80 mg/day for four weeks; or 3) receive haloperidol 20 mg/day for four weeks. Plasma levels will be determined at fixed intervals during both phases of treatment to assess the relationship between neuroleptic blood level and clinical response.